#
#  Copyright 2008-2009 NVIDIA Corporation
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.
#

def flatten(x):
    if hasattr(x, '__iter__'):
        for xi in x:
            if hasattr(xi, '__iter__'):
                for i in flatten(iter(xi)):
                    yield i
            else:
                yield xi
    else:
        yield x

def interleave(*args):
    iterators = [iter(x) for x in args]
    while iterators:
        for it in iterators:
            try:
                yield it.next()
            except:
                iterators.remove(it)
